Catalyst systems comprising a source of a Group VIII metal, a phosphine and a protonic acid are known for use in the carbonylation of acetylenically and olefinically unsaturated compounds. One type of catalyst system which has been disclosed comprises a source of a Group VIII metal, a pyridyl phosphine and a protonic acid.
European Patent Nos. A1-0259914 and EP-A1-0305012 discloses catalyst systems comprising a palladium compound, a pyridyl phosphine, an acid and a quinone and their use in the carbonylation of olefins to afford polymers. The examples illustrate the use of para-toluenesulfonic acid as the protonic acid.
European Patent No. A1-0282142 discloses the use of catalyst systems comprising a palladium compound, a pyridyl phosphine and a protonic acid in the carbonylation of olefins with hydroxyl-containing compounds. The examples illustrate the use of para-toluenesulfonic acid as the protonic acid.
European Patent No. A1-0271144 discloses the use of a catalyst system comprising a palladium compound, a pyridyl phosphine and a protonic acid in the carbonylation of acetylenes with hydroxyl-containing compounds. The examples illustrate the use of para-toluene sulfonic acid or benzene phosphoric acid as the protonic acid.
The Applicants have found that catalyst systems exemplified in European Patent No. A1-0271144 are poorly tolerant towards the presence of allene, which is a common impurity of unsaturated hydrocarbon compounds, especially acetylenes.
It has now been found that catalyst systems comprising a palladium compound, a pyridyl phosphine and an alkylsulphonic acid have outstandingly high activity in the carbonylation of acetylenically unsaturated compounds, and have improved tolerance towards the presence of allene.